In recent years there has been increased interest in both environmental protection and the conservation of both natural resources and synthetic materials through recycling.
One of the general classes of materials known to pose some of the greatest challenges to recyclers is synthetic polymers, such as plastics. This is largely due to the fact that their chemical nature materials makes them difficult to effectively and efficiently degrade to their constituent monomers, lower molecular weight oligomers, or other breakdown products, for reuse or safe disposal. The chemical nature of polymeric materials also make them difficult to handle, dispose of and/or recycle as their degradation products are often toxic or otherwise insulting to the environment.
Another factor making synthetic polymers difficult to recycle is their variety. Many degradation techniques may target depolymerization of only a limited number or type of polymeric materials, leaving others intact. Also, polymeric materials in the waste stream are often comingled with a wide variety of solid and liquid wastes which can foul recycling/disposal treatment processes. This factor can complicate attempts at large scale recycling of polymeric materials by requiring multiple process and/or separation steps.
In addition, synthetic polymeric materials, including polyethylene, polyvinylchloride, polystyrene, polypropylene and the like, make up a substantial portion of the waste generated by industry and municipalities. Accordingly, another aspect of the challenge to recycling or disposal of polymeric materials is the need to design recycling/disposal systems capable of functioning effectively on a scale sufficient to accommodate the volume and variety of polymeric materials in an industrial or municipal waste stream.
Beyond being able to render polymeric waste to disposable form, it is of course most desirable to be able to convert polymeric waste to reusable materials. In addition to being valuable as fuel, breakdown compounds of this type provide a ready feedstock for the preparation of detergents, lubricants and other, more valuable commodities Likewise, depolymerization products can also be used in the preparation of new polymers, such as plastics.
Accordingly, it is desirable to be able to chemically degrade a wide variety of polymeric materials, particularly those classes of materials that constitute the greatest portion of waste polymeric materials generated in industrial or domestic settings.
It is also desirable to be able to render waste polymeric materials to a form amenable to reuse. This may mean producing degradation products which are both capable of being used as starting materials in the production of new materials and which are also in suitable form for such reuse, considering ease and safety of handling, demands of relative purity, etc.
Another beneficial characteristic in recycling/disposal processes is the ability to carry out the process in the presence of solid and liquid waste contaminants. Also, it is advantageous to be able to carry out recycling/disposal processes without the use of higher temperatures in the vapor phase (less than thos needed for combustion), and without having to provide specialized atmospheres (e.g. absent oxygen), pressurized atmospheres, atmospheres using constant gas streams or specific pure gases or gas mixtures.
The many embodiments of the present invention make progress toward the accomplishment of the above objectives. In light of the present disclosure and/or the practice of the present invention, other advantages and/or the solution to additional problems, may become apparent to one skilled in the relative arts.